Macaca nemestrina is much sought after as a nonhuman primate model of AIDS and AIDS- related research. Few native born pigtails are available for biomedical research in the United States, and feral pigtail macaques are of dubious value to the research community. Simian retroviruses and other immune suppressive viral agents occur naturally in these macaques, and their presence makes the affected animal unsuitable as research subjects for AIDS-related projects and other viral infectious disease and vaccine research. Animals free of collateral infection with these viral agents are considered specific-pathogen- free (SPF). The goal of this project is to use feral M. nemestrina, free of SPF-target viruses, to rear a group of SPF defined progeny from which a domestic, self-sustaining, supply of research quality pigtail macaques can be obtained. The initial objective is to establish a breeding colony of SPF defined feral pigtail macaques capable of producing subsequent breeder stock of native born SPF M. nemestrina. The specific aims leading to this objective are: to screen, identify, and select suitable pigtail founders to stabilize an SPF breeding population of 140 females and 20 males from which a native born SPF colony can be later established; to maintain the founders as a SPF colony in an outdoor breeder configuration; to establish these animals in harem-breeder groups of 1 male to 7-10 females and immature offspring; to guarantee the health, SPF status and psychological well-being of all project animals; to maximize reproductive success of the colony and thus, establish a population of progeny from the feral SPF pigtails with a high probability of maintaining SPF status; to safeguard the health of personnel involved; to maximize containment and control of the SPF breeder complex; to continue to maintain AAALAC accreditation; to maintain computerized historical and demographic data on the colony and its members; and to provide appropriate security for the colony, its progeny and support facilities. Methods proposed to accomplish the long-term objective are to evaluate and select candidate feral pigtail macaques during a 90-day quarantine period and subsequently evaluate healthy animals for the SPF-target agent (Herpesvirus simiae; the retroviruses, HIV, SIV, STLV; and Malaria).It is anticipated that two feral pigtails will have to be evaluated to select one potential feral breeder candidate.Surveillance of the resulting SPF defined feral pigtails is scheduled at 3-month intervals for the first two years and biannually thereafter. Mother- reared progeny are to be evaluated for SPF status in an identical manner with all qualifying female offspring and select male progeny reared in expanding peer groups for future SPF breeder stock selection. Feral pigtails and progeny, which do not qualify for retention, and all excess male progeny which may be SPF defined, are to be made available to the biomedical research community.